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Posted by Robin Diaz on 11:02:41 07/28/07
Increased birdage this morning in Bill Baggs Cape Florida SP seemed to be a combination of migration and post-breeding dispersal. Birds that don't nest in the park were around (Blue Jays, Green Heron and Loggerhead Shrike) as well as true migrants; Blue-gray Gnatcatcher (15), American Redstart (3), Chimney Swifts, Purple Martins and Barn Swallows.
The Blue Jays are a head-scratcher. One-two birds are seen periodically in the park but not known to nest there. My records show that this species sometimes stages in fairly good numbers in the south end of the park -- but mid-September through mid-October. Kaufman (_Lives of North American Birds_) states that Blue Jays do not migrate farther south than the US, so I'm curious where "our" flocks go. Well-known and respected authors have written interesting papers on this subject. Some authors concede lack of good understanding on Blue Jay migration, while others indicate that most flocks of migrating Blue Jays consist of juvenile birds. Still others say that there is some contridiction on the age of birds that migrate. Apparently, 3 subspecies north of Florida may migrate, depending on food availability. To further muddy the issue, conspicuous movements of Blue Jays have been recorded in fall in extreme South Florida and the Keys but these are wandering juveniles rather than true migrants, according to Robertson, 1971. So, this morning's 8 birds' (5 & 3) composition, destination and purpose remain a mystery. But, as Blue Jays usually appear to me, they seemed up to no good!
Any thoughts are welcome other than "She has too much time on her hands if she's pondering such issues."
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